The present invention is concerned with a process of producing powdered metal parts. In particular, the process is concerned with removing the lubricants that are employed in the process of producing powdered metal parts.
During the preparation of powdered metal parts, various lubricants must be applied to the parts in order to assist in the sizing and proper shaping of the powdered metal parts. A difficulty has arisen in the field of powder metallurgy that the lubricant must be removed from proper handling and operation of the part. Due to the porosity of a powdered metal part, the lubricant has a tendency to penetrate deeply within the pores of the parts. U.S. Pat. No. 3,007,822 teaches that there is no known method for removing said oil. Therefore, when the part is subjected to heat treatment in order to cause the proper hardening of the metal, the lubricant has a tendency to ooze from the part, discolor the part, and carbonize onto the part, forming carbon scale. The carbonized substance detrimentally affects the operation of the powdered metal part and therefore must be removed by extremely costly methods such as grit blasting or to subject the part to an oxidizing atmosphere at high temperatures, which is extremely costly and in turn affects the hardening of the powdered metal part itself.
A number of patents discuss the problem of oil in powdered metal parts. U.S. Pat. No. 3,007,822 suggests that the pores of powdered metal parts be filled with an organic resin for successful plating. U.S. Pat. No. 3,290,124 suggests impregnating porous electrical discharge metal parts with plastic fillers. U.S. Pat. No. 2,155,592 teaches inserting waxlike substances into the pores of the powdered metal parts. U.S. Pat. No. 3,741,734 teaches impregnating sintered porous metal with solid additives by the liquid diffusion process. U.S. Pat. No. 3,853,491 teaches a liquid diffusion process to concentrate thoria content in filaments. U.S. Pat. No. 2,076,381 teaches porous tungsten being sintered in the presence of hydrogen saturated with water vapor to provide large crystal growth. U.S. Pat. No. 3,337,336 teaches a sintered zinc electrode being treated with a solvent water mix, which has a low dielectric constant so as to leach out impurities from amalgamated zinc anodes. U.S. Pat. No. 2,655,457 teaches hardening of sintered tungsten alloys by being quenched in water or oil. U.S. Pat. No. 2,897,097 teaches porous metal parts being filled with molten wax prior to metal plating of the part.
None of the above references suggests a convenient means for removal of a lubricant applied to a powdered metal part to assist in the sizing of said part.